Research into gas electron amplification type radiation detectors using pixel type electrodes is proceeding. In radiation detection by a conventional detector, large area and real-time imaging can not be sufficiently realized in image imaging of the detection region. On the other hand, the gas electron amplification type radiation detector is characterized by being capable of real-time image imaging with a large area.
Regarding the structure of the gas electron amplification type radiation detector, for example, reference can be made to Japanese Laid Open Patent Application Publication No. 2015-111057, Japanese Patent No. 3354551, Japanese Patent No. 4391391 and Japanese Patent No. 3535045.
In the radiation detector of Japanese Laid Open Patent Application Publication No. 2015-111057, as is shown in FIG. 6 of Japanese Laid Open Patent Application Publication No. 2015-111057, for example, a through hole is filled with a through electrode and an upper end is constricted by an insulating resin layer so that an anode electrode having a size smaller than that of the through electrode within the through hole is formed. However, in this structure, since the upper end part of the anode electrode where an electric field is the most concentrated is in contact with the resin layer, problems occurred such as an inability to obtain a sufficient electric field intensity or disorder of an electric field. As a result, it was difficult to stably obtain a high gas amplification ratio. That is, it was difficult to realize a radiation detector which could obtain a high-resolution radiation image having a high signal intensity and a high S/N ratio.